3GPP (Third Generation Partnership Project) has established the W-CDMA method as a standard third generation cellular mobile communication method, and a series of W-CDMA-based services are now started. HSDPA (High-Speed Downlink Packet Access) with higher communication speed has also been established as a standardized access method, and HSDPA-base service is now about to begin.
Meanwhile, an evolved form of the third generation radio access (Evolved Universal Terrestrial Radio Access hereinafter referred to as “EUTRA”) has been discussed in the 3GPP.
An OFDM (Orthogonal Frequency Division Multiplexing) method is suggested for application to a downlink in EUTRA.
An adaptive modulation/demodulation error correcting method (AMCS: Adaptive Modulation and Coding Scheme hereinafter referred to as “AMCS method”) based on adaptive radio link control (link adaptation) of channel coding, etc., is applied as an EUTRA technique to the OFDM method.
The AMCS method is the method of changing a radio transmission parameter (hereinafter “AMC mode”), such as error correcting method, coding factor in error correction, data modulation multivalue number, code spreading factor (SF) along the time/frequency axes, and multicode multiplexing number, depending on a propagation path condition at each mobile station to efficiently carry out high-speed packet data transmission.
For example, in data modulation, QPSK (Quadrature Phase Shift Keying) is changed to more efficient multivalue modulation, such as 8PSK and 16QAM (Quadrature Amplitude Modulation), as a propagation path condition improves. This increases the maximum throughput of a communication system.
Various communication methods, such as a multicarrier communication method and a single-carrier communication method, are suggested for application to an uplink in EUTRA. In suggested methods, the single-carrier communication method superior in PAPR (Peak to Average Power Ratio) characteristics is preferred to the multicarrier communication method, such as OFDM method.
FIG. 18 depicts a channel configuration of an uplink and a downlink that is assumed based on a suggestion from the 3GPP for EUTRA.
The downlink in EUTRA is composed of a downlink pilot channel DPiCH, a downlink synchronization channel DSCH, a downlink common control channel DCCCH, a downlink shared control signaling channel DSCSCH, and a downlink shared data channel DSDCH (Nonpatent Literature 1).
The uplink in EUTRA is composed of an uplink pilot channel UPiCH, a contention-based channel CBCH, and an uplink scheduling channel USCH (Nonpatent Literature 2).
In the downlink in EUTRA, the downlink pilot channel DPiCH includes a downlink common pilot channel DCPiCH and a downlink dedicated pilot channel DDPiCH.
The downlink common pilot channel DCPiCH is equivalent to a common pilot channel CPiCH in the W-CDMA method, and is used for estimation of radio propagation path characteristics, cell search, and measurement of propagation path loss in uplink transmission power control in executing the AMCS method.
The downlink dedicated pilot channel DDPiCH is transmitted from an antenna different from a cell shared antenna in radio propagation path characteristics, such as adaptive array antenna, to a dedicated mobile station device, or, when necessary, may be used for reinforcing the downlink common pilot channel DCPiCH in transmission to a mobile station device with a low reception quality.
The downlink synchronization channel DSCH is equivalent to a synchronization channel SCH in the W-CDMA method, and is used for cell search by a mobile station device, a radio frame for an OFDM signal, a time slot, a TTI (Transmission Time Interval), and OFDM symbol timing synchronization.
The downlink common control channel DCCCH is equivalent to a primary common control physical channel P-CCPCH, a secondary common control physical channel S-CCPCH, and a paging indicator channel PICH in the W-CDMA method, containing common control information, such as report information, paging indicator PI information, paging information, and downlink access information.
The downlink shared control signaling channel DSCSCH is equivalent to a control information channel of a high-speed physical downlink shared channel HS-PDSCH in the HSDPA method. The downlink shared control signaling channel DSCSCH is shared by a plurality of mobile station devices, and is used for transmitting information (modulation method, spreading code, etc.) necessary for demodulation in a high-speed downlink shared channel HS-DSCH, information necessary for an error correction/decoding process and an HARQ (Hybrid Automatic Repeat Request) process, radio resources (frequency, time) scheduling information, etc., to each mobile station device.
The downlink shared data channel DSDCH is equivalent to a packet data channel of the high-speed physical downlink shared channel HS-PDSCH in the HSDPA method, and is used for transmitting packet data from a superior layer to a mobile station device.
In the uplink, the contention-based channel CBCH is equivalent to a random access channel RACH in the W-CDMA method.
The uplink scheduling channel USCH is composed of a shared control channel SCCH and a shared data channel SDCH, which are equivalent to an uplink dedicated physical data channel UDPDCH in the W-CDMA method and an uplink dedicated physical control channel for HS-DSCH (HS-UDPCCH) in the HSDPA method. The uplink scheduling channel USCH is shared by each mobile station device, and is used by the mobile station device to transmit packet data, downlink channel propagation path quality information CQI (Channel Quality Indicator), feedback information of HARQ, etc., an uplink pilot, and uplink channel control information.
The uplink pilot channel UPiCH is used for estimating uplink radio propagation path characteristics in the AMCS method.
FIG. 19 depicts a configuration of a downlink radio frame that is assumed based on a suggestion from the 3GPP for EUTRA.
A downlink radio frame has a two-dimensional configuration composed of Chunks that are groups of a plurality of subcarriers along the frequency axis, and time slots TTIs along the time axis. A Chunk consists of a group of subcarriers.
For example, when the spectrum BW of the whole downlink (downlink frequency bandwidth) is 20 MHz and the frequency bandwidth Bch of a Chunk is 1.25 MHz, the downlink radio frame contains 16 Chunks along the frequency axis.
When one radio frame is 10 ms and a TTI is 0.5 ms, one radio frame contains 20 TTIs along the time axis. One radio frame, therefore, contains 16 Chunks and 20 TTIs, and one TTI contains a plurality of OFDM symbol lengths (Ts).
Hence, in the case of FIG. 19, the minimum radio resources unit available to a mobile station device is made up of one Chunk and one TTI (0.5 ms).
Radio resources of one Chunk can be subdivided further.
As shown in FIG. 19, the downlink common pilot channel DCPiCH is mapped to be located at the head of each TTI. The downlink dedicated pilot channel DDPiCH is mapped to be located at a proper position in one TTI when necessary, according to an antenna use condition at the base station or a propagation path condition at a mobile station device (e.g., located at the center of TTI).
The downlink common control channel DCCCH and the downlink synchronization channel DSCH are mapped to be located at the head TTI of the radio frame. As a result of locating both channels at the head TTI of the radio frame, a mobile station device in an idle mode can receive common control information of cell search, timing synchronization, report information, paging information, etc., by receiving only the head TTI of the radio frame or several OFDM symbol lengths (Ts) in the head TTI of the radio frame. When in the idle mode, the mobile station device is allowed to carry out intermittent reception (IR) operation.
The downlink shared control signaling channel DSCSCH is mapped to be located at the head of each TTI, as the downlink common pilot channel DCPiCH is. This allows a mobile station device to carry out intermittent reception to receive only the downlink shared control signaling channel DSCSCH when the mobile station device is on packet communication but packet data addressed to the mobile station device is not present in each TTI.
The downlink shared data channel DSDCH is divided in Chunks, transmitting packet data addressed to each mobile station device based on the AMCS method. Each Chunk is assigned to each user (e.g., each of mobile station devices MS1, MS2, and MS3 shown in FIG. 19) according to a propagation path condition at each mobile station device.
A user scheduling method is suggested to improve the throughput of the entire system, by which method, as shown in FIG. 19, one Chunk is assigned as a unit Chunk to one user but Chunks more than one Chunk are assigned to a user of a mobile station device having better radio propagation path characteristics in time slots TTI_1 and TTI_2 to create a multiuser diversity effect. Another user scheduling method is also suggested to improve reception characteristics, by which method, as shown in FIG. 19, a plurality of Chunks and sub-TTIs are assigned as unit Chunks and TTIs to a plurality of users in time slots TTI_3, TTI_n−1, and TTI_n, in which a wider frequency bandwidth across a plurality of Chunks is given to a user of a mobile station device whose radio propagation path characteristics are inferior due to cell boundaries, high-speed movement, etc., to create a frequency diversity effect.
FIG. 20 depicts a configuration of an uplink radio frame that is assumed based on a suggestion from the 3GPP for EUTRA.
An uplink radio frame has a two-dimensional configuration composed of Chunks that are groups of a plurality of subcarriers along the frequency axis, and time slots TTIs along the time axis. A Chunk consists of a group of subcarriers. For example, when the spectrum BW of the whole uplink (uplink frequency bandwidth) is 20 MHz and the frequency bandwidth Bch of a Chunk is 1.25 MHz, the uplink radio frame contains 16 Chunks along the uplink frequency axis.
When one radio frame is 10 ms and a TTI is 0.5 ms, one radio frame contains 20 TTIs along the time axis. One radio frame, therefore, contains 16 Chunks and 20 TTIs, and one TTI contains a plurality of symbol lengths.
Hence, in the case of FIG. 20, the minimum radio resources unit available to a mobile station device is made up of one Chunk (1.25 MHz) and one TTI (0.5 ms).
Radio resources of one Chunk can be subdivided further.
As shown in FIG. 20, the uplink pilot channel UPiCH is mapped to be located at the head and the tail of each TTI of the uplink scheduling channel USCH.
The base station device estimates a radio propagation path and detects the synchronization between a mobile station device and the base station device from the uplink pilot channel UPiCH of each mobile station device.
Mobile station devices are allowed to simultaneously transmit the uplink pilot channels UPiCH using toothcomb-shaped spectrum (distributed FDMA), localized spectrum (localized FDMA), or CDMA.
The contention-based channel CBCH is divided in Chunks. When user data or control data not scheduled by the base station device is present, such data can be transmitted through the contention-based channel CBCH.
The uplink scheduling channel USCH is divided in Chunks. Each mobile station device subjected to scheduling by the base station device transmits packet data through the uplink scheduling channel USCH to the base station device, based on the AMCS method.
Each Chunk is assigned to each user (e.g., each of mobile station devices MS1, MS2, MS3, MS4, and MS5 shown in FIG. 20) according to a radio propagation path condition at each mobile station device.
A request item of EUTRA states a need of considering power consumption by a mobile station device (Nonpatent Literature 3).
Nonpatent Literature 4 presents a suggestion of controlling a period of transmitting/receiving control information and user data and a period of not transmitting/receiving control information and user data to suppress power consumption.    Nonpatent Literature 1: R1-050707 “Physical Channels and Multiplexing in Evolved UTRA Downlink”, 3GPP TSG RAN WG1 Metting #42 London, UK, Aug. 29-Sep. 2, 2005    Nonpatent Literature 2: R1-050850 “Physical Channels and Multiplexing in Evolved UTRA Uplink”, 3GPP TSG RAN WG1 Metting #42 London, UK, Aug. 29-Sep. 2, 2005    Nonpatent Literature 3: 3GPP TR (Technical Report) 25.913, V2.1.0 (2005-05), Requirements for Evolved Universal Terrestrial Radio Access (UTRA) and Universal Terrestrial Radio Access Network (UTRAN)    Nonpatent Literature 4: R2-061061 “DRX and DTX Operation in LTE_Active”, 3GPP TSG RAN WG2 Metting #52 Athena, Greece, Mar. 27-31, 2006